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GLIN==> Avon Point, Lake Erie, research update





August 14, 1999
                             John Lavelle
                             346 Inwood Blvd.
                             Avon Lake, Ohio  44012
                                 E-mail  aa4532@lcfn.org
      
                            

    Some quick notes on what is happening at Avon Point,
a shale reef in the Central Basin of Lake Erie between
the cities of Lorain and Cleveland Ohio. This a continuation
of two other notes posted on the GLIN-announce.

    I have not made as taken as many bottom samples this 
year as in previous ones for two reasons: One, the Lake 
has been rough (higher waves) then in previous years and
the amount of detritus and plankton has also been much 
greater. Two, I've now been able to use a boat to go
off shore with and it is a learning process in how
to dive and take the samples from the boat (also I am
trying to teach myself underwater photography which 
contributes to having less time for sampling).
    From a qualitative stands point this is what is 
happening on the reef to the middle of this year.
    The sponges have not appeared on the rock's surfaces
this year and only two small (about 5 cm2) brown sponges
have been seen on the rock's bottom surfaces. I think this
may be due to the increase in detritus and plankton in the
water than in any year so far.
    The rounded gobies are as plentiful as ever (about 10
to 15 per square meter on the rocky areas of the reef, 
though this number is hard to verify because the gobies are
attracted by my presence and tend to swarm around me when
I am on the bottom. There are few full grown ones but
pentiful little ones.
    The ablabsymia (midges) population appears to have
shot way up based on viewing the number of nests on the
rock's undersides. This too may be a result of the increased
plankton load>
    The Cladophora has been thicker and has lasted much longer
than in previous years.
    The bryozoan, F. Sultana is still common but not as 
common as last year.
    No snails have been seen at all this year.
    Very few planarians have been found.
    The number of hydras found in the late Spring and early 
Summer are still at very low numbers compared to the early
years of this study.




          COPEPODS FROM 1993 TO 1999, AVON POINT


    The samples so far this year for the crustacean copepods
for this area of the Lake give mixed readings. Whereas the
Calanoid copepods have seemed to have leveled off at low
numbers the cyclopoids have shown an increase in numbers.
Interestingly though the Nauplii of both families show a
decrease in numbers.


                       COPEPODS
                 Monthly Averages for Copepods
   The following data is based on 12.5 liter samples taken twice
a week. All the samples where taken in the morning from the
same location.
	        Calanoid Copepods 1993 to 1999
       1993      1994     1995        1996    1997    1998    1999
Jan.                                                          17.2
Feb.                                                            .29
Mar.                        2.2        2.6      .9    1.56      .25
Apr.             7.7        3.7        3.5     4.5    24.1     2.9 
May            104.3       84.8       37      40.5    11.6    15.2
June   12.75    71.4       56.7       60.7  *144      27.8    26.7
July    4.85    22.4        2.4       28.4     8.5     4.6     8.1
Aug     4       16.7        5         28.1     7.1     2.6
Sept   26.57    32.1       13.6        6.8    11      12
Oct    15.55    11           9.3      34.6     6.3    21
Nov     9.11     9.9        5.3        2.9     4.9    14.3
Dec     5.57     6.3        7.2        5.6      .8    20.1

Average of the  31.3       20.9      23.04    25.3    15.34
Calanoids Apr. thru Dec.
1994 to 1998

   *  Except for the extraordinary number of animals found on one
sampling date the number of calanoid copepods would have shown 
a marked decline in 1997. That date was June 15. The sample 
had the extraordinary number of 880 calanoids in the 12.5 liter
sample. The total number of calanoids found for the entire year 
in about 50 samples minus the June 15 date was 1130, thus the one 
sample had more animals than all the samples for the entire 
year. I have belabored the point of the nonrandomness of the
zooplankton in the 1996 report and so will not cover that ground
again. What I want to point out here is that if the June 15 sample
is dropped from the reporting than the copepods had a steep 
drop in their numbers in 1997 and the average for the month of  
June would be 52 per sample rather than 144 per sample. The 
average for the year would drop from 25.3 per sample to 11.4
per sample. Whether this dropping of the sample from the total
counts is valid I leave up to the reader but if the June 15
sample is ignored than the calanoids have had a major decline 
in 1997.

                    Cyclopoid Copepods
  The table does not include the cyclopoid T. Mexicanus pranis. 
This small copepod was found very sporadically in the samples 
until this year. Though when it was found it could be found 
in large numbers.
     Comparison of Cyclopoids Copepods from 1993 to 1999
      1993       1994        1995    1996      1997   1998   1999
Jan.                                                          3
Feb.                                                          2.3 
Mar.                                                          1.4
April             8.6        9.77     3	        .3     2.1    2.4
May              38.33      56.75    50.33     8.9    34.7   24.6		
June   51.5      38.77     182      109.36    35.4    59.1   89.2  
July   25        26.6       19.55    17.13    30.2     6.3  111.4*
Aug.   38.5      13.7       19.11     5	       7.7     3.7
Sept.  17.28     12.5        7.12    17.33     2.9     1.2
Oct.    8.55     13.1        3.77     8.88     2.3     3.4
Nov.   12.88      7.7        5.66     1.5      4.3     1.6
Dec.   10.71      5.13       4.4      7.66     1.1     3.3

Average for the  18.277     34.23    24.46    10.3    12.82
years 1994 to 1998
Apr. to Dec.

*The average for July, 1999 is skewed by one sampling date (July 14)
which a total of 638 cyclopoids in the sample. Eliminating the 
one sample from the average for the month gives a new monthly 
average of 23.7.
   A further note on this sample. After taking the plankton
sample from off the jetty I went out in a boat about a 1/2 mile
from shore to get the benthic sample in about 15 feet of water.
The number of cyclopoids in that 5 liter sample was 184. 
Multipling this by 2.5 to make it equal the plankton sample gives
a total of 460. Meaning this massing of cyclopoids in the area
probably covered a large area. The cyclopoids totals taken from
each sample for the month of July were:

July 5  45
8       21
11       1
14     638
21      60
25       7
28       8
Avg    111.4


                   Copepod Nauplii
    No attempted was made to distinquish between cyclopoid and 
calanoid copepods. 
                        Nauplii
Monthly averages
         1993      1994       1995       1996   1997    1998    1999
Jan.                                     3.25    3.8     0.3     0.4
Feb.                                      .75    1.9     1.4      .29
Mar.                                     9.5     1.4      .9      .25
Apr.               36.16      28         8.25   61.3    33.4    36.8
May               133.97     161.25     63.55   13.8    53.4    20.1
June     13        61.3      129.44    121.22   64.8    38.5    17.1
July     2.71      27.66      29.4      51      48.6     5.2     4.4
Aug.     4.5       49.55      70.44     30      15       9.8
Sept.    6.57      26         40.12     49.66   10      38.4
Oct.     4.77      10.22      13.11     44       8.8    14.8
Nov.     6.44       2.88       4.44      1.625   2.8     1.4
Dec.     4.57       5.62       2.4       1.66     .2      .25

Yearly average     39.26       53.17     41.21   25.03  16.26
from Apr to Dec.

                       ROTIFERS AT AVON POINT

     This too is a continuation of the report posted on the
GLIN - annouce awhile back. I have not here broken out the 
rotifers by genus as I did in the second posting on the GLIN.
Even with the lumping together of all the rotifers it can be
easily seen that for some reason the rotifer numbers have been 
cut more than in half from what they were in previous years.
I know very little about these little critters and therefore
will not even hazard a guess as to why their population has 
fallen so.

   Plankton sample size 12.5 liters
   In the chart below the number column is the total 
number of all rotifers found in the month. The average
is the total rotifers divided by the total number of
samples taken that month. Generally there were two samples
taken every week or 8 to 9 samples a month
              
           1994               1995            1996          
      number  average   number  average  number  average 
April   60      10        75     8.33     250    31.25
May     78       8.6     660    82.5    *1362   151.33
June   532      48.36    491    54.55    1335   148.33
July *4144     460.44    501    55.66    2787   348.37
Aug   2065     229.44    176    19.55    2697   385.28
Sept   124      15.5     379    47.38    1217   135.22
Oct     82       9.11    279    31        267    29.66
Nov.    66       7.3     102    11.33     103    12.87
Dec.     1        .12      3     0.6       10     1.11

            1997             1998           1999
      number  average   number  average   number   average
Jan     13      2.2        3     0.5        1        .02
Feb      0      0          4     0.6        0        0
Mar      6       .7        3     0.3        4        .057
Apr.    36      4        310    38.8       208     26
May    726     38       2594   324.3      1009    112
June  2229    247.7     1274   141.6       593     65.9
July  1271    141.2     1610   178.9       151     21.6
Aug.   707    101       1793   224.3
Sept  1245    155.6      970   121.5
Oct.   759     84.3      925   102.8
Nov.    11      1.2       37     4.1 
Dec.     3       .3        2      .25
* The July 1994 and the May 1996 are so high because in
both these month on one date there was an enormous
number of rotifers.
  July 20 1994 there were 3043 rotifers in just one 12.5 
liter sample.
  May 26 1996 there were 1073 rotifers in the sample.


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